1. Field of the Invention
The present invention relates to a sintered sputtering target used for forming a high purity metal Mo thin film, and a high purity metal Mo coarse powder being suitably used as a raw material for making the sintered target powder. The highly pure metal Mo thin film is suitably used for forming a transparent electroconductive film of a flat panel display, such as a liquid crystal display, a gate electrode of a field effect transistor, a wiring circuit, or the like.
2. Description of the Related Art
In a production of the sintered sputtering target for forming the high purity metal Mo thin film, a high purity metal Mo powder having a high purity of 99.99 or more % by mass and an average particle diameter of 2 to 4 μm by the Fischer method has been conventionally used as the raw material powder, (hereinafter, the average particle diameter shows the results by the Fischer method).
Moreover, it has been also known that the high purity metal Mo powder is produced,    using a molybdenum trioxide powder, an ammonium molybdate powder or the like, which have the high purity of 99.9 or more % by mass and the average particle diameter of 2 to 4 μm, as the raw material, (hereinafter, these powders are said generically to as a MoO3 powder),    forming a molybdenum dioxide powder (hereinafter, it is said to as MoO2) by carrying out a primary hydrogen reduction process to the MoO3 powder under conditions that the predetermined time is kept at 500 to 700 degree C. in a hydrogen gas stream, and    carrying out a secondary hydrogen reduction process to the MoO2 powder under conditions that that the predetermined time is kept at 750 to 1100 degree C. in the hydrogen gas stream.
Furthermore, it has been also well known that the sintered sputtering target for forming the high purity metal Mo thin film is produced, using the high purity metal Mo powder, that is, the high purity metal Mo powder having the high purity of 99.99 or more % by mass and the average particle diameter of 2 to 4 μm by the Fischer method as the raw material, and    carrying out a hot isostatic pressing (hereinafter, it is said to as HIP) to this Mo powder which is pressed to make a green compact at a pressure of 200 to 300 Mpa. (For example, see Japanese Unexamined Patent Application Publication No. Hei 2-141507)